The term femoral fractures is here taken to signify intertrochanterian, subtrochanterian and supracondylar fractures, i.e. fractures at different places of the thigh bone (femur).
In order to promote the healing of femoral fractures, use has been made for a relatively long time of various types of screws or pins for fixing the loose bone pieces in such mutual positions that the growing together of the bone pieces across the sides of the fracture is promoted.
In intertrochanterian fractures or fractures which are both inter-trochanterian and subtrochanterian, the orthopedist has, to support the bone pieces around the fracture, often chosen in accordance with techniques hitherto employed to use a fixation device (implant) comprising a screw and an angled plate with which the screw is connected. The screw is passed, via a bore, into the head of the femur and is thereafter screwed in place therein. The plate is secured to the femur by means of screws of considerably smaller dimensions than the previously mentioned screw. The head of the femur and the femur proper have thereby obtained mutually fixed positions even if the fixation device permits a certain, very limited possibility for sliding in the longitudinal direction of the neck of the femur. On the other hand, the plate secured to the femur has always been arranged to realize a completely rigid fixation of the plate in the longitudinal direction of the femur.
While operations in which such fixation devices are applied normally give the desired outcome, it is not uncommon that problems occur because of excessive loading on the fixation device. Excessively high loading entails, for example, that the plates or their anchorage screws break off, that the smaller anchorage screws are projected out of their holes in the bone some time after the operation or that the large screw up through the neck of the femur cuts through the surface definition of the head of the femur towards the hip joint. Such problems are naturally extremely negative, involve pain to the patient and often entail that a new operation must be carried out.
Moreover, the technique disclosed in the immediately preceding paragraphs entails the disadvantage that the fracture surfaces after being subjected to loading, are occasionally fixed in positions in which the surfaces do not fit into one another, a factor which both prolongs and impedes the healing process. This results in bone shortening, lameness and difficulties in walking.